These dyno graphs come courtesy of Supersprint who dyno'd the new C7 RS6 with the 4.0 TFSI twin turbo V8 and the previous generation C6 RS6 with the 5.0 liter TFSI twin turbo V10. The previous generation V10 model was rated at 571 horsepower. The current model with the smaller 4.0 liter V8 is rated by Audi at 553 horsepower. The dyno graphs from Supersprint which were done on a MAHA dyno show that the previous generation car has just slightly over 3 more horsepower.

What is interesting is the 4.0 TFSI actually shows more torque than the 5.0 liter V10. Additionally, despite the torque advantage and the corrected horsepower figures being about 3 horses apart the wheels figures (the blue line) show a difference of 74.8 wheel horsepower which does not make much sense and does not appear to be accurate. The MAHA dyno automatically calculates losses and crank horsepower figures so let's just stick with the crank figures as they seem to be the most accurate.

Basically, the two cars are showing very similar power outputs. Audi was able to go smaller with the 4.0 liter V8 yet is not giving up much of anything. As APR's tuning results show, the 4.0 TSFI is a monster. Ditching the V10 has turned out to not be the step backward enthusiasts initially suspected it would be.

This is true, although the V10 has monster potential. There's several that have been pushed to over 1000whp now, and only with turbo upgrades/bolt-ons. I still kind of wish we at least had one model with that engine over here. Or that maybe they had kept for the current-gen S8. Problem is, I think the 4.0 is a newer engine, the V10 is basically the old 4.2 (which itself is ancient, and was derived from the original 4.0) with two extra cylinders. But it was a damn good engine. The new one should be a beast though. Once the turbo upgrades start coming, we may see 1000 whp from it too.

AFAIK, Supersprint's MAHA dyno is a chassis dyno, so the wheel horsepower is what is actually being measured. The crank horsepower is estimated based on the automatically calculated drivetrain losses. The only way to get a true engine output figure is to remove the engine from the car and use an engine dyno.

This is true, although the V10 has monster potential. There's several that have been pushed to over 1000whp now, and only with turbo upgrades/bolt-ons. I still kind of wish we at least had one model with that engine over here. Or that maybe they had kept for the current-gen S8. Problem is, I think the 4.0 is a newer engine, the V10 is basically the old 4.2 (which itself is ancient, and was derived from the original 4.0) with two extra cylinders. But it was a damn good engine. The new one should be a beast though. Once the turbo upgrades start coming, we may see 1000 whp from it too.

Agreed on the V10 and I think I'd ultimately prefer it but the 4.0 is showing some serious strength.

AFAIK, Supersprint's MAHA dyno is a chassis dyno, so the wheel horsepower is what is actually being measured. The crank horsepower is estimated based on the automatically calculated drivetrain losses. The only way to get a true engine output figure is to remove the engine from the car and use an engine dyno.

I really don't care about engine dyno figures as the car isn't going to move without the drivetrain so wheel figures are all that matter to me.

However, there is something off with these wheel figures and the MAHA crank figures are the right ones. There isn't a 70+ wheel difference between the two and the RS6 isn't putting out 380 to the wheels and that doesn't translate to 577 crank horsepower anyway.